Most rail fans are specifically made to comply with customer specifications and the expected harshness of rolling stock railway environments. Others are simply upgraded versions of standard fans such as the Ecofit GRF single inlet forward centrifugal fan.
The GRF was primarily designed for operating with HEPA filters for pharmaceutical applications and toxic environment filtration systems. It consists of a high power external rotor motor fitted in a standard single inlet scroll assembly.
In order to provide extra stability for the over-sized motor, Ecofit adapted a double shaft motor (normally found in a double inlet configuration) and added an air inlet guard and double shafts to hold the motor on the scroll. The result is a rather odd-looking but very efficient assembly, which even with a standard power of over 400Watts still complies with the forthcoming Energy Related Products ErP 2015 directive (only applicable for the standard ref).
The railway version is an upgrade from this assembly. The standard design is already suited to resist the vibrations that are generated on railway applications; the upgrade benefits from improved environmental protection, increased from IP54 to IP56, for humidity, dust and water ingress protection, as well as a polyzinc black finish on the motor, impeller, scroll, guard and back plate.
The fan motor has been lowered to 250Watts, and accommodates a 2 speed control by winding, depending on the wiring (delta or star connection). The unit is electrically resistant to voltages peaks, with the fan cable compliant to railway applications standards.